Can Oracle compare Credit limit with Amount of specific lines that are selected during Launch Pick R

 Scenario:

Customer Credit limit = 600/-

SO Line 1 Amount  200

SO Line 1 Amount  300

SO Line 1 Amount  400

SO Line 1 Amount  100

Total Order Line Limit 1000/-

When I select Line 3 and 4 (Total 500/-), Oracle does not compare this amount with 600/- and instead compares 1000/- with 600/- and puts ALL lines on hold. Is there any workaround to ensure Oracle compares Credit limit with Amount of  lines that are  specifically selected during Launch Pick Release?